1. Field of Invention
The present invention relates to the structures of supporting board, and more particularly to a light weight supporting board for playyard, pen, cot, and bed, which has a rigid, simple and strong structure to evenly distribute and support a downward force of a user""s weight in lower cost.
2. Description of Related Arts
Referring to FIG. 1A, a boundary frame, such as playyard, pen, cot and bed, incorporated with a conventional supporting board is illustrated, wherein the supporting board is supported by the boundary frame. Usually, the supporting board is made of wood or is a cardboard that can support a user such as a young child thereon. However, the conventional supporting board has several drawbacks.
The supporting board is bulky and heavy for storage and transportation. In order to provide a rigid structure for supporting the user""s weight, the supporting board must be constructed to have a high tension supporting surface. It is worth to mention that the tension supporting surface provides a predetermined tension force evenly distributed thereon, wherein when the downward force which is the user""s weight is greater than the tension force, the supporting board will be cracked or even broken.
Especially for the playyard, the young child may jump on the supporting board. Since the supporting board is rigid but not flexible, the concentrated downward force exerted on the supporting board will easily crack the thereof. Therefore, the rigid supporting board may not be the best solution for the playyard or the like.
Some supporting boards made of cardboard having a lighter weight feature can be easily and quickly unfolded for use and fold into a compact unit for carriage. However, the fold-up structure of the supporting board cannot provide the high tension supporting surface. In other words, such supporting boards cannot rigidly support the user thereon.
Alternatively, the supporting board can be constructed by a plurality of parallel bars transversely supported on the boundary frame, as shown in FIG. 1B, such that a mattress can be rigidly supported on the supporting board.
Moreover, since the supporting board is made of wood which is one of the most valuable raw resources in the world, it is unreasonable to keep wasting the resource until it may be used up one day. So, an alternative is sought for.
A main object of the present invention is to provide a light weight supporting board for playyard, pen, cot, and bed, which has a rigid, simple and strong structure to evenly distribute and support a downward force of a user""s weight in lower cost.
Another object of the present invention is to provide a light weight supporting board for playyard, pen, cot, and bed, wherein the supporting board has a durable and elastic ability for providing a high tension supporting surface to enhance the durability of the supporting board.
Another object of the present invention is to provide a light weight supporting board for playyard, pen, cot, and bed, which provide a substantial support without altering or complicating the original structure of the playyard, pen, cot, and bed.
Another object of the present invention is to provide a light weight supporting board for playyard, pen, cot, and bed, wherein no expensive or mechanical structure is required to employ in the present invention in order to achieve the above mentioned objects. Therefore, the present invention successfully provides an economic and efficient solution for providing reinforced supporting configuration to the user supported on the playyard, pen, cot, and bed.
Accordingly, in order to accomplish the above objects, the present invention provides a light weight supporting board for playyard, pen, cot, and bed, which comprises:
a supporting pocket comprising a first layer having a tension surface and a second layer overlapped with the first layer to define a receiving cavity between the first layer and the second layer;
a boundary frame defining a central window and having a size and shape adapted to be fittedly received in the receiving cavity so as to mount the first layer covering the central window to form the tension surface; and
means for retaining a predetermined tension on the tension surface of the supporting pocket, wherein the tension must be larger than a weight to be supported by the supporting board.